Carburetor



Aug. 30, 1966 R. w. SUTTON CARBURETOR Filed Jan. 10, 1964 INVENTOR. 2 026 7'; )4/ 5212 1 071 ,7 fray/r1574 United States Patent 3,269,712 CARBURETOR Robert W. Sutton, Grosse Pointe Farms, Mich., assignor to The Bendix Corporation, Zenith Carburetor Division, Detroit, Mich., a corporation of Delaware Filed Jan. 10, 1964, Ser. No. 337,093 2 Claims. (C].261--41) The present invention relates generally to carburetors for internal combustion engines, and more particularly to an improved fuel discharge system for such carburetors.

It is an object of the present invention to provide an idle system for a carburetor which uses relatively few additional parts, occupies a relatively small space, is readily and inexpensively manufactured and which is highly responsive in operation.

It is a further object of the present invention to provide an idle system which cooperates with the main fuel discharge system to improve the transition from one system to the other and to improve the fuel distribution from the main system.

These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in connection with the appended drawings in which:

FIGURE. 1 is a sectional view through a carburetor embodying the present invention, and

FIGURE 2 is a view of the idle tube assembly shown in FIGURE 1.

Referring to the drawing, numeral designates a carburetor having an air horn .12, a main body 14 and an induction passage 16, in which are respectively mounted a choke valve 18, and a throttle valve 20 on shafts 22 and 24. A float bowl or source of fuel 26 is provided wherein the fuel level is maintained by a suitable float 28. An air nozzle 30 is mounted in the induction passage upstream of the throttle valve 20 and is provided with converging entrance walls 32 which lead to a throat 34 from which extends a substantially constant cross sectional flow path 36 defined by a skirt portion 38 of nozzle 30. The skirt 3-8 is spaced substantially equidistantly from the walls 40 of induction passage 16 so as to define an annular space 42 between the skirt and walls. Skirt 38 is provided with a pair of diametrically opposed ports 44 and 46. Fuel from the float bowl 26 passes through main metering restriction 48 to main fuel discharge jet 50 which has a discharge orifice 52 disposed to overlap port 44 such that orifice 52 is exposed to both the pressures in flow path 36 and in the annular space 42. The main jet is provided with a high speed air bleed 54. A afloat bowl vent is shown at 56:

An idle tube 58 is mounted concentrically with main jet 50 and has an inlet 60 disposed below the fuel level in float bowl 2-6. Idle tube 58 projects from main jet 50 through ports 44 and 46, in air nozzle 30 entirely across the flow path 36 and induction passage 16 into the Wall 40 of the induction passage where the end 58' of idle tube 58 acts as a channel plug and thereby eliminates a separate plug which would otherwise be necessary. The idle tube outlet 62 is connected by means of conduit 64 to the idle discharge port or aperture 66 the size of which is controlled by a conventional idle needle 68. Second idle discharge port 70 connects conduit 64 with the induction passage 16 immediately upstream of the throttle valve 20 when the throttle is in closed position. The main idle bleed is provided at 7-2 in tube 58 and is exposed to the pressure in annular space 42.

In operation during idling, fuel from float bowl 26 passes through main metering restriction 48 into inlet 60 through idle tube 58, outlet 62, conduit 64 and is dis- 3,269,712 Patented August 30, 1966 charged from port 66 and at times also from port 70. When the throttle 20 has been opened a sufficient amount that air flow through nozzle 30 creates a zone of low pressure substantially co-extensive with the flow path 36 of sufliciently low value to cause fuel to be discharged from the main jet 52, the flow through the idling system gradually ceases. In many conventional systems when the main discharge system is functioning air is bled through the idle system into the main system such that the idle system is void of fuel thereby causing a time lag in shifting back to the idle system should the throttle valve be closed again. In the present invention the main idle air bleed 72 is located at substantially the same pressure level as the discharge orifice 52 of the main discharge jet so as to minimize or eliminate the tendency of back bleeding through the idle system.

Air flow across idle tube 52 causes the pressure to be somewhat reduced immediately downstream of the tube whereby fuel from the main discharge jet 50 is caused to run along the downstream side of tube 58 and to be discharged therefrom in a substantially uniformly distributed pattern to promote better mixing and evaporation of the fuel. The location of the idle tube 58 not only assists in the distribution of the fuel discharge from the main jet, but also facilitates the manufacture of the carburetor. As shown in the drawing only one additional hole need be drilled in the walls 40 of induction passage 16 to permit the idle tube to be readily inserted in the main jet. The separate idle well and additional drilled passages in the walls 40 of the induction passage normally required in conventional carburetors are eliminated by the present invention. The idle tube is so constructed that the body 73 also serves as a channel plug.

Although only one embodiment of my invention has been described, it will become readily apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention.

I claim:

1. A carburetor for an internal combustion engine comprising:

a source of fuel,

an induction passage,

a throttle valve mounted in said passage,

a flow nozzle mounted in said passage upstream of said throttle valve and having a discharge skirt portion extending therefrom in spaced relation to the walls of said passage,

a pair of diametrically opposed ports formed in said skirt,

a fuel discharge jet connected to said source of fuel and extending into one of said ports,

an idle tube projecting from said jet through said ports to traverse the flow path through said flow nozzle, an air bleed in said tube opening into the space between said skirt portion and the wall of said passage, and

means connecting said idle tube to said passage downstream of said throttle valve.

2. A carburetor for an internal combustion engine comprising:

a source of fuel,

an induction passage,

a throttle valve mounted in said passage,

a flow nozzle mounted in said passage upstream of said throttle valve and having a discharge skirt portion extending therefrom in spaced relation to the walls of said passage,

a pair of diametrically opposed ports formed in said skirt,

a main fuel discharge jet connected to said source of an idle tube projecting from said jet through said ports 3 4 fuel and having a discharge orifice overlapping one References Cited by the Examiner of said ports whereby said orifice is exposed to the UNITED STATES PATENTS pressures existing in said nozzle and in the space 1,307 5 5 1919 Guidfif 261 63 between said skirt portion and the walls of said pas- 5 1,453,490 5/ 1923 'Bessom.

Sage, 1,703,932 3/1929 Ayers.

' 2,737,935 3/1956 Olson 26141 X 2,759,716 8/1956 Jones 26l41 to traverse said passage,

an air bleed in said tube opening into the space between 10 FOREIGN PATENTS said skirt portion and the walls of said passage, and 9,742 7/ 1923 Netherlandsmeans connecting said idle tube to said passage down- HARRY B. THORNTON, Primary Examiner.

stream of said throttle valve. T. R MILES, Assistant Examiner, 

1. A CARBURETOR FOR AN INTERNAL COMBUSTION ENGING COMPRISING: A SOURCE OF FUEL, AN INDUCTION PASSAGE, A THROTTLE VALVE MOUNTED IN SAID PASSGE, A FLOW NOZZLE MOUNTED IN SAID PASSAGE UPSTREAM OF SAID THROTTLE VALVE AND HAVING A DISCHARGE SKIRT PORTION EXTENDING THEREFROM IN SPACED RELATION TO THE WALLS OF SAID PASSAGE, A PAIR OF DIAMETRICALLY OPPOSED PORTS FORMED IN SAID SKIRT, A FUEL DISCHARGE JET CONNECTED TO SAID SOURCE OF FUEL AND EXTENDING INTO ONE OF SAID PORTS, AN IDLE TUBE PROJECTING FROM SAID JET THROUGH SAID PORTS TO TRANSVERSE THE FLOW PATH THROUGH SAID FLOW NOZZLE, AN AIR BLEED IN SAID TUBE OPENING INTO THE SPACE BETWEEN SAID SKIRT PORTION AND THE WALL OF SAID PASSAGE, AND MEANS CONNECTING SAID IDLE TUBE TO SAID PASSAGE DOWNSTREAM OF SAID THROTTLE VALVE. 